The present invention concerns a dimension-measuring column, notably a single vertical axis column, as well as a method for entering commands to switch the measure mode in such a column.
Columns for measuring vertical dimensions are frequently used in mechanical workshops or in industry for measuring different vertical coordinates of a work-piece. An example of measuring column 1 is represented diagrammatically in FIG. 1. The shown column comprises a probe tip 44 mounted on a measuring carriage 3 and brought into contact with the piece to be measured 9 as well as a vertical displacement mechanism (not represented) allowing this probe tip to be displaced along the vertical axis z. The vertical displacement mechanism can be manual or motorized according to the model. A measuring and displaying system 7 enables the vertical position of the probe tip to be determined and displayed on a display 70. The system 7 also allows the pressing force of the probe tip against the work-piece 9 to be measured. The measuring system uses for example a capacitive, inductive, magneto-resistive or optical sensor comprising for example a scale against the supporting frame 2 and a sensor in the carriage 3.
Usual measuring columns have a supporting frame 2 of a height comprised between 50 centimeters and 2 meters and allow the vertical position of the probe tip 44 to be measured with an accuracy on the order of the micron. The piece to be measured 9 is placed close to the measuring column 1 and the probe tip is displaced vertically so as to rest against the portion of the work-piece whose vertical coordinate one wishes to measure. The measuring column 1 can be mounted on an air-cushion base 20 that facilitates its horizontal displacement. Such measuring columns are described for example in the documents U.S. Pat. No. 4,924,598. Such measuring columns are further commercialized by the applicant under the name MICRO-HITE (registered trademark) and TESA-HITE (registered trademark) for example.
Current measuring columns are often provided with a control panel 7 comprising control keys 71 for entering different commands. The control panel includes a microprocessor capable of executing a computer program for commanding the displacements of the carriage 3, the measuring and the displaying of the results. The commands that can be entered by means of the control panel 7 are interpreted by a microprocessor that executes a computer program for commanding the displacements of the carriage 3, the measuring and the displaying of the results. The entered commands allow for example to displace the measuring carriage, to display the absolute height of a point or the difference between two measuring points. Other commands enable the measure mode or display mode to be switched. Different examples of useful measure modes are described in the patent U.S. Pat. No. 3,895,356. One useful measure mode that is sometimes encountered allows the turn-back points to be measured, i.e. the lowest and the highest point of a hole or rod, and the height difference between these two extremes to be calculated. The available display modes make is possible for example to chose between metric or imperial units or to display the probe tip""s pressing force rather than its position.
The handling of the control keys 71 on a control panel is not very intuitive; the number of buttons is considerable when many measure and display modes are available. The operator""s eyes must leave the piece to be measured in order to select the button to actuate. Furthermore, it is necessary to let go of the piece 9 or of the measuring column 1 to enter a command to switch the measure mode.
Columns are also known that are provided with a turning control button (crank) 8 that allows the vertical displacements of the probe tip 44 to be controlled. The control button 8 can easily be used without having to be watched. Its diameter and position are chosen so as to allow a good hold on the measuring column 1 with a single hand on the button 8. The commands that can be entered with this button are however restricted to vertical displacements of the measuring carriage.
Measuring columns are also known that are provided with a command wheel (not represented) close to the turning control button 8 and allowing commands to activate the turn-back point search mode. In this mode, the piece to be measured 9 or the measuring column 1 is then displaced horizontally, whilst maintaining the resting pressure between the probe tip 44 and the work-piece, so as to scan the area close to the extrema by overshooting at least once the turn-back point. An extreme-computing algorithm determines the vertical coordinate of the turn-back point; an acoustical and/or optical signal confirms that the point""s vertical coordinate has been calculated. The operator must then actuate the command wheel to deselect the automatic turn-back point search mode, then displace the probe tip to perform a new measurement. This measure mode is very useful for measuring the diameter of a hole or of a rod, for example.
These systems have the inconvenience of requiring an additional command wheel which increases the cost of the system and whose use is not very intuitive. Furthermore, it is necessary to let go for a while of the turning control button 8 to actuate the control wheel.
It is thus an aim of the present invention to propose a method for entering commands to switch the measure mode in a column for measuring vertical dimensions that avoids the inconveniences of the prior art methods, as well as a measuring column that is improved and easier to use than the measuring columns of the prior art.
According to the invention, these aims are achieved by means of a method and of a measuring column having the characteristics of the corresponding independent claims, variants of preferred embodiments being moreover described in the dependent claims.
In particular, these aims are achieved by means of a method enabling a command to switch the measure mode to be entered in a dimension-measuring column, wherein this mode-switch command is entered only by acting on the angular position of a turning control button.
This method has the advantage that the mode switch is effected by moving the turning control button towards a predetermined angular position, different from the angular position range used for vertically displacing the probe tip. The mode-switch commands can thus be entered without it being necessary to let go of the turning button.
The The dimension-measuring column of the invention can function according to a limited and discrete number of different measure modes that can be selected by means of one of the turning control buttons. Each measure mode can furthermore call for continuous or quasi-continuous parameters that depend for example on the angular position of the turning control button between two predetermined thresholds.
The turning control button used is preferably constituted by the crank allowing the probe tip to be displaced vertically. The invention thus notably consists in using this crank not only for vertically displacing the probe tip but also for entering commands to switch the measure mode.
The command to switch the measure mode is effected preferably each time the turning control button passes through one or several predetermined angular positions. Thus, whatever the vertical position of the carriage, a command to switch the measure mode can be entered by bringing the turning control button exactly in the same angular position. This way of functioning has the advantage of being very intuitive.
In a preferred embodiment of the invention, a tactile reaction, for example a sudden change of the rotation torque, is perceived by the operator when the control button passes through the predetermined position causing a mode switch. In this manner, a command to switch the measure mode can be entered without the eyes leaving the piece to be measured or the screen displaying the results.
In a preferred embodiment of the invention, different mode-switch commands can be entered by having the turning control button pass twice through the same angular position during a time interval of limited duration. It is thus possible to increase the number of different commands that can be entered.